Selectivity, efficiency, and underwater observations of modified trap designs for the snow crab ( Chionoecetes opilio) fishery in Newfoundland and Labrador

Abstract

Comparative fishing experiments were conducted to evaluate the selectivity and efficiency of escape mechanisms installed in traditional snow crab ( Chionoecetes opilio) traps. Performance of the different trap types (control, traditional, experimental) were compared on the basis of size distribution caught, numbers of animals per trap haul (CPUE N), and size selectivity. The study demonstrated that either 95 or 100 mm diameter escape mechanisms installed into traditional 14.0 cm mesh traps resulted in 38–47% fewer undersized pre-recruit (<95 mm CW) crab being captured, with no significant difference in the capture efficiency of standard (95–101 mm CW) or premium sized crab (>101 mm CW). Qualitative underwater behavioural observations were also conducted for snow crab in response to baited traps, corroborating current understandings as well as documenting new observations related to crab behaviour during capture, escape, haul-back, and interspecific competition with Atlantic cod ( Gadus morhua).